Health behaviour among adolescents in Denmark: influence of school class and individual risk factors

AIMS: The aim of this study was to assess the relative influence of school class on health behaviour among adolescents versus that of the family's socioeconomic status and individual factors among adolescents. METHODS: The material comprised 3,458 students in grades 8 and 9 in 244 school classes. Data were collected through questionnaires completed by the students and by their class teacher and information from the school physician. Multilevel analysis was used to indicate the relative significance of individual and school class characteristics. RESULTS: We find no consistent pattern between the mother's socioeconomic status and the included health behaviour measurements; however, adolescents from the lower socioeconomic groups had a higher risk of unhealthy dietary habits and adolescents whose mothers were unemployed had a significantly lower risk of drinking alcohol weekly versus all other adolescents. Not living with both biological parents, focusing on friends, and not being very academically proficient were associated with an increased risk of harmful health behaviour. Health behaviour varied substantially between school classes, especially for daily smoking, weekly alcohol consumption, and use of hashish and other euphoriants. Circumstances in the school class more profoundly influenced risk behaviour among adolescents (smoking, alcohol consumption, and use of hashish or other euphoriants) than their dietary habits (eating breakfast, frequent intake of fruit and vegetables, and frequent intake of soft drinks). CONCLUSIONS: The school class had the relatively strongest influence on adolescents' risk behaviour (smoking, alcohol intake, and use of hashish or other euphoriants), whereas family circumstances comprised the strongest influence on dietary habits.